The disclosure relates generally to additive manufacturing, and more particularly, to a quality control test feature including a metal powder sample capsule for metal powder additive manufacturing.
The pace of change and improvement in the realms of power generation, aviation, and other areas has accompanied extensive research for manufacturing components used in these fields. Conventional manufacture of metallic components generally includes milling or cutting away regions from a slab of metal before treating and modifying the cut metal to yield a part, which may have been simulated using computer models, and drafting software. Manufactured components which may be formed from metal can include, for example, airfoil components for installation in a turbomachine such as an aircraft engine or power generation system. The development of additive manufacturing, also known in the art as “3D printing,” can reduce manufacturing costs by allowing such components to be formed more quickly, with unit-to-unit variations as appropriate. Some devices fabricated via additive manufacture can be formed initially as several distinct components at respective processing stages before being assembled in a subsequent process. Among other advantages, additive manufacture can directly apply computer-generated models to a manufacturing process while relying on less expensive, and/or raw materials.
Some forms of additive manufacturing (AM) allow a component to be formed from a bed of fine metal powder positioned on a build platform, which is processed by an electron beam or laser (for example, using heat treatment such as sintering) to form a component or sub-component. One challenge with respect to AM using metal powder, and especially processes that reuse metal powder, is ensuring quality of the part being built. As shown in FIG. 1, conventionally, a number of test features 14, 16, 18, 20 for testing various aspects are additively manufactured with one or more production parts 10 (shown as round structures) on a single build platform 12 using the same build parameters, e.g., up skin, down skin, hatch, etc. The test features may be used to track powder and metal compliance with the AM specifications and part quality. For example, a quality control part 14 identical to production part 10 may be built for metallographic evaluation; a tensile bar 16 (wider outer ends with narrow middle) may be built to allow for mechanical property testing; a cylindrical or rectangular test bar 18, equal to the height of production part 10, may be used to record downtime witness features and to measure surface roughness and/or hardness; and a powder sample capsule 20 may be built to capture a sample of unfused metal powder for powder quality retention and analysis of powder chemistry and particle size.
The test features present a number of challenges. For example, each test feature 14, 16, 18, 20 is built simultaneously with but separate from production parts 10 and separate from one another. Accordingly, each test feature takes up valuable space on build platform 12, and consequently may reduce the quantity of production parts 10 printed on the build platform. Additionally, making each test feature takes time away from manufacturing the production parts, and uses valuable metal powder. With specific regard to powder sample capsule 20, additional challenges include providing sufficient support for the capsule. Typically, the capsule is built on a large foundation 22 on build platform 12. Current practice to remove the capsule from the platform requires wire electro-discharge machining (EDM), which can damage the capsule. Further, conventional capsules must be mechanically cut open, which can present handling issues for the metal powder, e.g., spillage, air distribution, etc. The described challenges can render the metal powder sample unusable for testing, e.g., due to exposure and/or contamination.